Are you feeling tightness in the chest, shortness of breath or a galloping heartbeat? Don't panic, it's not a heart attack.

By:Darby Saxbe

It can come out of nowhere. You're shopping for groceries or buckling your seat belt when suddenly your muscles contract and your heart begins to pound.

Panic attacks can be both bewildering and terrifying, but they're not unusual. An estimated 2.4 million people experience one every year. It may begin as tightness in the chest, shortness of breath or a galloping heartbeat. Many sufferers believe they are having a heart attack and rush to the emergency room.

The cause of an attack can be unclear, but they often arise in the face of major life changes, such as childbirth or a new job. Attacks may also follow trauma.

Prevalence rates have been on the upswing since the 1950s, although many experts believe what seems like a trend is simply better diagnosis.

What is a panic attack?

More than a feeling of anxiety, a panic attack produces distinctive physical symptoms. Each person experiences panic differently, but most people report intense fear accompanied by bodily sensations that can range from a racing heart to nausea and dizziness. Panic can come on suddenly or slowly and usually lasts no more than 20 minutes at its peak.

What causes a panic attack?

Scientists believe panic attacks stem from the brain's "fight or flight" system gone awry, often ignited by stress or a traumatic event. In our high-octane society, that response can kick in with no real threat in sight or after the source of stress is long gone.

Research suggests that chronic panic sufferers may be easily flummoxed by their bodily sensations. Someone vulnerable to panic might interpret a rapid heartbeat as a heart attack. If fear overwhelms her, the symptoms intensify in a vicious cycle.

Does it run in families?

Vulnerability to anxiety may have a biological basis. If a parent or sibling has panic attacks, a person's risk increases by about sixfold. A Yale study found that panic attack sufferers had fewer serotonin receptors in their brains, while other studies suggest those with anxiety may have overly sensitive "suffocation alarm systems," which detect a shortage of oxygen even under normal conditions.

What is panic disorder?

Panic attacks are so frightening that sufferers will do just about anything to avoid another. That may mean staying away from situations associated with anxiety. Someone who once panicked on an airplane might decide not to fly. But the fear often extends to other settings; the plane phobic might start to dread cars and buses as well.

People with full-blown panic disorder, in which attacks are a frequent problem, feel constantly vulnerable, which forces them to be vigilant.

Only about a third of people who get occasional panic attacks will go on to develop panic disorder. Even though men and women report the attacks with equal frequency, women are twice as likely to get the disorder.

Some scientists think Irritable Bowel Syndrome (IBS) may be linked to panic disorder. Because IBS can be uncomfortable and embarrassing, sufferers dread their next IBS attack and become highly sensitive to their digestive system. When something feels awry, their agitation mounts, causing real stomach upset and pain. Since both panic and IBS symptoms are highly stress-sensitive, sufferers of either condition might find themselves trapped in a feedback loop.

How can I cope?

Antidepressant medication may help alleviate panic. However, cognitive-behavioral therapy may work even better; researchers estimate that up to 80 percent of panic sufferers can be helped by psychotherapy alone.

Therapists often treat panic by exposing the patient to feared settings of increasing intensity. Exposure therapy can also include exposure to the physical sensations of panicâspinning clients in circles to make them dizzy, having them inhale carbon dioxide or breathe through a straw or jog to raise their heart rates. Once clients learn that those feelings do not signal impending doom, they can better withstand panicâand eventually prevent it altogether.